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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    while (true) {
      let uname = prompt('请输入用户名：')
      let password = prompt('请输入密码：')
      if (uname === 'admin' && password === '123456') {
        alert('用户登录成功！')
        break
      }
    }
  </script>
</body>
</html>